Effects of Different Mineral Admixtures on the Properties of Fresh Concrete

Table 1

Comparison of physical and chemical properties of OPC and mineral admixtures.

	OPC	FA	GGBS	SF **	MK	RHA	Remarks
Specific gravity	3.05 [48]	2.2–2.8 [28]	2.79 [48]	2.6–3.8	2.5	2.11 [44]	The specific gravity of mineral admixtures is generally lesser than cement. Therefore, more volume is obtained when mineral admixture replaces the cement.
SiO2, %	20.44	35–60* [28]	34.4 [48]	91.4	53.87	88.32 [44]	Amounts of SiO2 and Al2O3 are maximum in SF and RHA showing their reaction capability with the primary hydrate of cement
Al2O3, %	2.84	10–30* [28]	9.0 [48]	0.09	38.57	0.46 [44]
Fe2O3, %	4.64	4–20* [28]	2.58 [48]	0.04	1.4	0.67 [44]
CaO, %	67.73	1–35 [28]	44.8 [48]	0.93	0.04	0.67 [44]
MgO, %	1.43	1.98 [28]	4.43 [48]	0.78	0.96	0.44 [44]
SO3, %	2.20	0.35 [48]	2.26 [48]	0.01 [49]	—	—
Na2O, %	0.02	0.48 [48]	0.62 [48]	0.39	0.04	0.12 [44]
K2O, %	0.26	0.4 [48]	0.5 [48]	2.41	2.68	2.91 [44]
MnO, %	0.16	—	—	0.05	0.01	—
TiO2, %	0.17	—	—	0.0	0.95	—
Particle size***, 𝜇m	10–40 [16]	≤45 [28]	—	0.1 [42]	0.5–20 [50]	11.5–31.3 [44]	Smaller particle size within concrete causes a greater surface area to react more effectively with the alkaline environment [3].
Specific surface (m^2/g)***	1.75 BET surface area	5–9 BET surface area [51]	0.4–0.599 BET surface area [48, 52]	16.455 BET surface area	12.174 BET surface area	30.4–27.4 [44] BET surface area	RHA, SF, and MK have the highest specific surface area. This results in highly dense and impermeable concrete with RHA, SF, and MK.; The BET surface area is affected by the carbon content of the SF and FA (higher carbon, higher surface area) [42].
Loss on ignition, %	1.8	0.3–3 [28]	1.32 [48]	2.0	1.85	5.81 [44]	Higher carbon content results in higher LOI in mineral admixtures [42].
Pozzolan reactivity	—	0.875 [53]	0.040 [53]	1.288	1.342	—	Pozzolan reactivity (gm of Ca(OH)2 consumed per gm of pozzolan) chapelle test [53].

∗If the sum of SiO₂ and Al₂O₃ and Fe₂O₃ exceeds 70%, then it will be classified as ASTM C618 Class F FA; however, if the sum exceeds 50%, then it will be classified as ASTM C618 Class C FA [28]. The CaO content is generally higher than 20% in Class C FA [28].
**The chemical composition of SF varies with the type of alloy that is being produced [42].
***Particle size and specific surface of mineral admixtures vary and greatly depend on grinding mill and duration of grinding.